List all registered events

I’m just getting started with writing an app. I know that you can register your own events and create event listeners. The core events that are available are listed here:
https://docs.nextcloud.com/server/latest/developer_manual//basics/events.html#available-events

Say other apps register their own custom events. How would I list all events currently registered with NC so I can interact with them and explore?

you can’t, any maybe you also shouldn’t because your app code would depend on another application and the event classes can change any time